Non-newtonian photo-curable ink composition

ABSTRACT

A non-Newtonian photo-curable ink composition that includes a polymerizable FMOC material in an amount ranging from about 2 wt % to about 20 wt % by total weight of the ink composition, a photo-initiator, an organic solvent and water, wherein the ink composition hasa first dynamic viscosity ranging from 25 cps to 10,000 cps at a first state and a second dynamic viscosity ranging from 1 cps to 50 cps at a second state. Also described herein is a method for making such non-Newtonian photo-curable ink composition and a method for producing printed images using such non-Newtonian photo-curable ink composition.

BACKGROUND

Inkjet technology has expanded its application to high-speed, commercialand industrial printing, in addition to home and office usage, becauseof its ability to produce economical, high quality, multi-coloredprints. This technology is a non-impact printing method in which anelectronic signal controls and directs droplets or a stream of ink thatcan be deposited on a wide variety of substrates. Inks used in suchtechnologies can be liquid dispersions, solution, or emulsions and caninclude oil-based inks, non-aqueous solvent based inks, water-based inksand solid inks Current inkjet printing technology involves forcing theink drops through small nozzles by thermal ejection, piezoelectricpressure or oscillation, onto the surface of a media. The deposited inkdroplets are, then, dried, e.g., using heat or forced air, or allowed todry at ambient conditions.

Curing of ink by radiation and, in particular, ultraviolet (UV) curing,has become popular. In these cases, special ink is used and the image iscured by exposure to a radiation source. The uses of suchradiation-curable (or photo-curable) inks and the curing process arerapidly becoming an alternative to the established printing process.Accordingly, investigations continue into developing radiation-curableink compositions that exhibit, when printed, specific and excellentprinting properties such as, for example, jetting properties as well asimproved adhesion.

DETAILED DESCRIPTION

The present disclosure refers to a non-Newtonian photo-curable inkcomposition that comprises a polymerizable FMOC material in an amountranging from about 2 wt % to about 20 wt % by total weight of the inkcomposition, a photo-initiator, an organic solvent, and water whereinthe ink composition has a first dynamic viscosity ranging from 25 cps to10,000 cps at a first state and a second dynamic viscosity ranging from1 cps to 50 cps at a second state. The present disclosure refers also toa method for making such non-Newtonian photo-curable ink composition andto a method for producing printed images using such non-Newtonianphoto-curable ink composition.

Before particular examples of the present disclosure are disclosed anddescribed, it is to be understood that the present disclosure is notlimited to the particular process and materials disclosed herein. It isalso to be understood that the terminology used herein is used fordescribing particular examples only and is not intended to be limiting,as the scope of protection will be defined by the claims and equivalentsthereof. In describing and claiming the present composition and method,the following terminology will be used: the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Concentrations, amounts, and other numerical data may bepresented herein in a range format. It is to be understood that suchrange format is used merely for convenience and brevity and should beinterpreted flexibly to include not only the numerical values explicitlyrecited as the limits of the range, but also to include all theindividual numerical values or sub-ranges encompassed within that rangeas if each numerical value and sub-range is explicitly recited. Forexamples, a weight range of about 1 wt % to about 20 wt % should beinterpreted to include not only the explicitly recited concentrationlimits of 1 wt % to 20 wt %, but also to include individualconcentrations such as 2 wt %, 3 wt %, 4 wt %, and sub-ranges such as 5wt % to 15 wt %, 10 wt % to 20 wt %, etc. The percent are by weight (wt%) unless otherwise indicated. As used herein, “image” refers to marks,signs, symbols, figures, indications, and/or appearances deposited upona material or substrate with either visible or an invisible inkcomposition.

The ink composition according to the present disclosure is anon-Newtonian photo-curable ink composition. As used herein, the term“ink” refers to a composition that can be colorant free or that can,alternatively, include colorant. Therefore, it should be noted that whenreferring to an “ink” or an “ink composition” this does not infer that acolorant necessarily be present. The ink composition is photo-curable orUV-curable or radiation-curable ink composition. By “curable”, it ismeant here that said ink can be cured. The term “cure”, in the contextof the present disclosure, refers to a process of converting a liquid,such as ink, into a solid by exposure to actinic radiation such asphoto-radiation, e.g., ultraviolet (UV) radiation. Such ink compositionsare commonly referred to as “energy-curable” inks to distinguish themfrom “solvent-based” inks In the uncured state, ink compositions arereadily jetted. However, upon exposure to suitable source of curingenergy, for example ultraviolet (UV) light, electron beam energy, and/orthe like, there is a formation of a cross-linked polymer network.

The ink compositions of the present disclosure are non-Newtonianphoto-curable inkjet ink compositions, meaning thus that they can beused in inkjet printing systems. Indeed, the ink composition asdescribed herein can be printed via inkjet technology as the viscosityof the non-Newtonian ink compositions can be lowered using shear orthermal forces within an inkjet printhead. Once exiting the printhead,the viscosity of the non-Newtonian compositions rapidly increases (e.g.within a few seconds or immediately) via self-assembly of polymerizableFMOC materials within the non-Newtonian ink compositions.

The ink composition is a non-Newtonian ink composition. The wording“non-Newtonian” refers to a composition where the viscosity of thecomposition can be manipulated by physical forces. The viscosity (themeasure of a fluid's ability to resist gradual deformation by shear ortensile stresses) of non-Newtonian fluids is dependent on an appliedforce such as shear or is dependent on applied thermal forces. Forexample, shear thinning fluids decrease in viscosity with increasingrate of shear or with increasing rate of heat. The non-Newtonian inkcomposition as described therein can show, therefore, these same shearthinning effects, under the fluid ejection conditions in whichcomposition is moved between the fluid container and the printhead of aninkjet device for example. In some other examples, the compositions canshow these same thermal thinning effects, when the compositions areheated during printing, e.g., at the fluid container or at the printheadof an inkjet device. Such non-Newtonian properties allow thecompositions to be used for printing via inkjet technologies whileachieving superior viscosity upon printing. In some examples, thepresent non-Newtonian photo-curable ink composition can be thinned byincreasing the temperature of the composition. In inkjet printingapplications, the ink composition is moved between a fluid container andthe printhead of an inkjet device. In these applications, the inkcompositions can be heated at the fluid container, between the fluidcontainer and the printhead, or in the printhead, thereby decreasingviscosity allowing for inkjet printing followed by rapid cooling andstructured network reformation on a recording medium.

By the term “non-Newtonian composition”, it is meant also that thecomposition comprises a structured network that can have differentbehavior depending on the force that is applied to the composition. Asused herein, “structured network” refers to the three dimensionalstructure that can be formed, as illustrated herein, by thepolymerizable FMOC materials present in the non-Newtonian inkcomposition. In such examples, the three dimensional structure isdependent upon mechanical and/or thermal forces. The mechanical and/orthermal forces, such as shear energy or heat energy, weaken thestructured network resulting in the viscosity changes based on theamount of force applied, as discussed herein. In some examples, thestructured network can be considered as a gel. The reformation of astructured network after printing can allow, for the presentnon-Newtonian inks, a better optical density than achieved by Newtonianink compositions. Once printed, the polymerizable FMOC material canre-form a structured network. Further, the ink has a first dynamicviscosity ranging from 25 cps to 10,000 cps at a first state and asecond dynamic viscosity ranging from 1 cps to 50 cps at a second state.The first dynamic viscosity is higher than the second dynamic viscosity.As mentioned, these structured systems show non-Newtonian flow behavior,providing useful characteristics for implementation in an ink-jet inkbecause of their ability to shear or thermal thin for jetting. Oncejetted, this feature allows the jetted drops to become more elastic-, orgel-like when they strike the media surface. These characteristics canalso provide improved media attributes such as colorant holdout on thesurface.

In some examples, the non-Newtonian photo-curable ink composition is anaqueous ink composition, meaning thus that it contains a certain amountof water as solvent. The amount of water in the ink composition isdependent, for example, on the amount of other components of the inkcomposition. The amount of water in the ink composition includes theamount of water added plus the amount of water in the suspensions andother components of the ink composition. In some examples, the amount ofwater in the ink composition is in the range of about 10 to about 90 wt% by total weight of the ink composition, in some other example; in therange of about 20 to about 80 wt % by total weight of the inkcomposition and, in yet some other example, in the range of about 30 toabout 70 wt %.

The non-Newtonian photo-curable ink composition as described hereinexhibits good printing properties. When used in inkjet printing device,the ink composition results in printed articles that have good bleed,edge acuity, feathering, and superior optical density/chroma (due, forexample, to low penetration on the media (paper for example)).Furthermore, the non-Newtonian photo-curable ink composition asdescribed herein can be printed on a broad selection of substratesincluding untreated plastics, flexible as well as rigid, poroussubstrates such as paper, cardboard, foam board and textile and has agood adhesion on said variety of substrates. The ink composition has agood viscosity that enables good printing performances and enables theability to formulate inks suitable for inkjet application. Thephoto-curable ink composition of the present disclosure enables thushigh printing speed and is very well suited for use in digital inkjetprinting. When printed on a substrate and cured, said ink compositionhas improved adhesion, specifically, on non-polar surfaces, for example.The composition possesses also good scratch resistance andweatherability. It can support high curing speed and has a viscosityenabling good jetting properties.

The non-Newtonian photo-curable ink composition of the presentdisclosure has the ability to produce high optical density for a lowerthan usual amount of ink deposited on the page in the same time whileproviding excellent durability performances. In addition, thenon-Newtonian photo-curable ink composition of the present disclosurehas excellent printing and durability performances while not requiring,for examples, the use of fixer fluids or the use of a pinning stepduring the printing process.

Furthermore, the non-Newtonian photo-curable ink composition asdescribed herein has the ability to exhibit high ink efficiency whilebeing independent of the nature of the media used. The ink compositionwould have thus high ink efficiency while being able to be printed ondifferent substrates. The non-Newtonian photo-curable ink compositioncan be used on paper substrate, for example, or on other type of media.The ink composition can be used in non-coated recording substrate.Indeed, very often, recording media have a variety of additives andcoatings applied thereon in order to provide acceptable quality whenused in printing applications. Therefore, the ink composition describedherein allows reliable jetting, fast drying and curing, ability to printon various media substrates while having excellent image quality andadhesion. The present non-Newtonian photo-curable ink composition of thepresent disclosure can thus provide excellent ink efficiency (opticaldensities) independent of the media used.

As used herein, “viscosity” refers to dynamic viscosity unless otherwisestated. It should be noted that for all viscosity measurements herein,unless otherwise stated, 25° C. is the temperature that is used. Suchviscosities can be measured using an Anton Paar Rheometer or a CAP2000rheometer from Brookfield Instruments. As discussed herein, theviscosity for non-Newtonian fluids are not discrete but change based onthe thermal or mechanical energy applied to the fluid: the addition ofheating and/or mechanical forces can alter, e.g. lower, the viscosityprofiles of the inks For the present inks, the viscosity can be, forexamples, measured at two states: at a first and at a second state. Mostof the time, the first dynamic viscosity will be higher than the seconddynamic viscosity. The “first state” refers when the ink is at a firststate, e.g. proximate in time when at rest (subject to shear rate of 5s⁻¹) or at room temperature (e.g. 23-25° C.). The “second state” referswhen the ink is at a second state, e.g. proximate in time to when atsignificant shear (shear rate of 10,000 s⁻¹) or at elevated temperature(e.g. 50° C.). The viscosity of the non-Newtonian photo-curable inkcomposition is thus measured at two states at a first state (e.g. atrest) and at a second state (e.g. at a processing state).

As such, the present composition can be subject to thinning under shearand/or heat in order to reduce the viscosity and allow the inks to beprocessed in an inkjet printing apparatus. In one example, the viscosityof the first state can be higher than 10,000 cps (such as at least20,000 cps, at least 100,000 cps, or even at least 500,000 cps). Thus,shearing and/or heating can alter, e.g. lower, the viscosity profiles ofthe present inks

The non-Newtonian photo-curable ink composition of the presentdisclosure has thus a first dynamic viscosity ranging from 25 cps to10,000 cps at a first state and a second dynamic viscosity ranging from1 cps to 50 cps at a second state. The non-Newtonian photo-curable inkcomposition can also have a first dynamic viscosity ranging from 100 cpsto 1,000 cps at a first state and a second dynamic viscosity rangingfrom 1 cps to 25 cps at a second state.

In some examples, the non-Newtonian photo-curable ink composition has adynamic viscosity ranging from 25 cps to 10,000 cps at a temperature of25° C. (first state) and a dynamic viscosity ranging from 1 cps to 50cps at a temperature of 50° C. (second state). In some other examples,the non-Newtonian photo-curable ink composition has a dynamic viscosityranging from 100 cps to 1,000 cps at a temperature of 25° C. and adynamic viscosity ranging from 1 cps to 25 cps at a temperature of 50°C. In addition, the ink composition can have a dynamic viscosity rangingfrom 25 cps to 10,000 cps at a shear rate of 5 s⁻¹ (or 1/s) (firststate) and a dynamic viscosity ranging from 1 cps to 50 cps at a shearrate of 10,000 s⁻¹ (second state). The ink composition can also have adynamic viscosity ranging from 25 cps to 2,000 cps at a shear rate of 5s⁻¹ (or 1/s) and a dynamic viscosity ranging from 1 cps to 20 cps at ashear rate of 10,000 s⁻¹, when measured at 25° C. At an even highershear rate range (>50,000-100,000 s⁻¹), the dynamic viscosity of theinks can drop further, e.g. from 1 to 10 cps. As such, high shear ratesor other mechanical or thermal forces can enable reliable jetting frominkjet printheads.

When little or no dynamic pressure is being applied to the ink to moveit through the system or when no heat is being applied to the ink, theink has a viscous consistency. However, when the normal amount ofdynamic pressure (˜ at least 10,000 Pascals) is applied to the ink tomove it through the inkjet system or when the ink is heated to 50° C. ormore, the ink viscosity can change significantly, e.g. from 25 to 5 cpsor from 10 to 2 cps. Thus, when such inks are ejected at a highfrequency from the fluid container of an inkjet fluid dispensing device,for example, the dynamic viscosities of the inks are at a low level thatdoes not interfere with the ejection process of the inkjet system.

In some examples, the present disclosure refers to an aqueous inkcomposition having non-Newtonian properties comprising a photo-initiatorand a structured network that is formed by FMOC material that comprisesa polymerizable or curable amino acid or peptide. The fact that the inkcomposition has non-Newtonian properties means herein that the viscosityis modified (i.e. reduced) when the composition is submitted to shearand/or heat.

Polymerizable FMOC Material

The non-Newtonian photo-curable ink composition, comprises apolymerizable FMOC material. By “polymerizable FMOC material”, it ismeant herein a polymerizable fluorenylmethoxycarbonyl (i.e. FMOC)material. The wording “polymerizable” means herein that the FMOCmaterial can be polymerized under specific condition, such as forexample, under UV radiation. The polymerizable FMOC Material is, forinstance, a curable FMOC Material, i.e. a radiation-curable material. As“radiation-curable”, it is meant that the material can be cured byexposure to actinic radiation such as photo-radiation, e.g., ultraviolet(UV) radiation. The curing step will result in a formation of across-linked polymer network. The source of radiation can be, forexample ultraviolet (UV) light, electrons beam energy, and/or the like.

The polymerizable FMOC Material can also be considered herein as actingas a “gelator” or “gelling agent” since it confers a structure similarto a gel to the ink composition (a gel being a liquid of a rather highviscosity that has difficulties to flow at normal (i.e. room) conditionsand temperature).

In some examples, the non-Newtonian photo-curable ink compositioncomprises polymerizable FMOC Material in an amount ranging from about 2wt % to 20 wt % by total weight of the non-Newtonian inkjet ink. In someother examples, the polymerizable FMOC Material can be present in anamount of about 3 wt % to 15 wt %, or of about 5 wt % to about 10 wt %by the total weight of the non-Newtonian photo-curable ink composition.

In some examples, the polymerizable FMOC material (i.e.fluorenylmethoxycarbonyl material) has the Formula 1, wherein R₁ is apolymerizable component.

In some examples, R₁ is a polymerizable or curable amino acid orpeptide. The FMOC material of the present disclosure that comprises thusa polymerizable or curable amino acid or peptide. Such amino acid can bean aliphatic amino acid such as glycine, alanine, valine, leucine, orisoleucine or a cyclic amino acid such as proline. The amino acid canalso be a hydroxyl or sulfur/selenium-containing amino acid such asserine, cysteine, selenocysteine, threonine, or methionine. The aminoacid can also be an aromatic amino acid such as phenylalanine, tyrosine,or tryptophan or a basic amino acid such as histidine, lysine, orarginine.

In some other examples, the polymerizable component R₁ is a curableL-phenylalanine (Phe). The polymerizable FMOC material will thus be apolymerizable FMOC-Phe system, i.e. a polymerizableN-(9-fluorenylmethoxycarbonyl)-L-phenylalanine, or a curable FMOC-Phesystem, i.e. a curable N-(9-fluorenylmethoxycarbonyl)-L-phenylalanine.

In yet some other examples, the polymerizable component R₁ isN-methacryloyl 3,4-dihydroxy-L-phenylalanine methyl ester. Thepolymerizable FMOC Material will have thus the Formula 2.

In some other examples, the polymerizable component R1 isα-Vinyl-DL-phenylalanine. The α-Vinyl-DL-phenylalanine (CAS[152774-49-7]) is available from FCH group or synthesis via procedure asdescribed in “Synthesis of α-Vinyl Amino Acids” (Methods in MolecularMedicine; 1999, Vol. (Iss), p. 467-88; Berkowitz and all). Then, thevinyl phenylalanine can be combined with 9-fluorenylmethyl chloroformate(FMOC-C1, CAS 28920-43-6, Available from Aldrich), in aqueous dioxane inthe presence of sodium carbonate or bicarbonate as per Carpino, (JACS,92:19, Sep. 23, 1970, p. 5748). The polymerizable FMOC Material willhave thus the Formula 3.

In some examples, the non-Newtonian photo-curable ink compositioncomprises a polymerizable FMOC material that is a polymerizable FMOC-PHEsystem (N-(9-fluorenylmethoxycarbonyl)-L-phenylalanine). In some otherexamples, the non-Newtonian photo-curable ink composition comprises apolymerizable FMOC material that contains N-methacryloyl3,4-dihydroxy-L-phenylalanine methyl ester or α-Vinyl-DL-phenylalanineas a polymerizable group.

In some examples, the polymerizable FMOC material could be a(S)-3-(FMOC-amino)-5-hexenoic acid, available Sigma-Aldrich, having theFormula 4 below.

In some other examples, the polymerizable FMOC material could be aFMOC-O-allyl β-serine having the Formula 5:

Such FMOC-O-allyl β-serine could be obtained as described in “Thesynthesis of FMOC-O-allyl b-serine; Y. Bergman; Tetrahedron: Asymmetry19 (2008) 2861-2863”.

In some examples, the polymerizable FMOC material could be synthesizedby reacting a polymerizable amino acid, such as3-methacryloyl-(l)-lysine (commercially available from PolysciencesInc.) with a 9-fluorenylmethyl chloroformate as illustrated below.

Polymerizable monomers containing amine or alcohol functional groups canbe used to form the amide or ester of the carboxylic acid group of anyFMOC amino acid. The following is an example of making an amidederivative using 2-aminoethyl methacrylate.

The HCl salt of 2-aminoethyl methacrylate can be commercially, forexample, available from Polysciences Inc. Other monomers, available alsofrom the Polysciences Inc., include diallylamine; N-hydroxyethylacrylamide; and 2-hydroxyethyl methacrylate. Diallylamine would reactwith the FMOC amino acid to give an amide derivative, as in the exampleabove. The N-hydroxyethyl acrylamide and 2-hydroxyethyl methacrylatewould react through the hydroxyl group with the FMOC amino acid to formthe ester derivative. R₂ in the reaction above would be the remainingportion of any amino acid.

Diallyamine:

N-hydroxyethyl acrylamide:

2-hydroxyethyl methacrylate:

Organic Solvent

The non-Newtonian photo-curable ink composition comprises organicsolvents. As used herein, “organic solvent” refers to any organicsolvent or mixture thereof. As such, the term organic solvent includessystems of solvents. The present organic solvents are in addition to anywater present in the non-Newtonian ink composition. Without being linkedby any theory, it is believed that the solvent has many functions suchas, for examples, helping with drop reliability and providing decapperformance, but also helping to have a good paper curl control.

In some examples, the organic solvent is present, in the non-Newtonianphoto-curable ink composition of the present disclosure, in an amountranging from about 3 wt % to about 50 wt % based on the total weight ofthe ink composition. In other some examples, the organic solvent ispresent in an amount ranging from 5 wt % to 40 wt % or ranging fromabout 10 wt % to 30 wt% by total weight of the ink composition.

The non-Newtonian photo-curable ink composition comprises organicsolvents and water. The amount of water, in the non-Newtonianphoto-curable ink composition of the present disclosure, can be in therange of about 10 wt % to about 90 wt % by total weight of the inkcomposition, or in the range of about 20 wt % to about 80 wt %; or inthe range of about 30 wt % to about 70 wt % by total weight of the inkcomposition.

The non-Newtonian photo-curable ink can also be an aqueous ink where theorganic solvent is present in an amount ranging from 5% to 50% by weightbased on the total weight of the non-Newtonian gel-based inkjet ink.

Examples of organic solvents that can be used include methanol, ethanol,propanol, iso-propanol, a glycol ether having at least about four carbonatoms, C4-8 alcohols, 1-methoxy-2-propanol, 2-methoxy ethanol, 2-ethoxyethanol, 1-methoxy-2-acetoxy propane, ethyl lactate, a glycol ether(optionally having at least about 10 carbon atoms), a dihydric alcohol(optionally having at least about 2 carbon atoms), tripropylene glycolmonomethyl ether, tripropylene glycol-n-butyl ether, propylene glycolphenyl ether, 2-pyrrolidinone (2P), 1-(2-hydroxyethyl)-2-pyrrolidinone(2HE2P), glycerol polyoxyethyl ether (LEG-1),1,3-Bis(2-Hydroxyethyl)-5,5-Dimethylhydantoin (Dantocol®DHE),2-methyl-1,3-propanediol (MPdiol), ethylhydroxy-propanediol (EHPD),glycerol, 1,5-pentanediol, 1,2-pentanediol, thiodiglycol, sulfolane,1,3-dimethyl-2-imidazolidinone, caprolactam, ethylene glycol, diethyleneglycol, triethylene glycol, tetraethylene glycol, propylene glycol,dipropylene glycol, tripropylene glycol, trimethylene glycol, butyleneglycol, hexylene glycol, polyethylene glycol, polypropylene glycol,glycerol, 1,2,6-hexanetriol, ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, diethylene glycol monomethyl ether, diethyleneglycol monoethyl ether, diethylene glycol dimethyl ether, and mixturesthereof. Additionally, organic solvents can be classified as networkparticipating solvents and network non-participating solvents. As usedherein, “network participating solvent” refers to organic solvents thatincrease viscosity of the non-Newtonian ink composition, measured at anyfunctional shear rate. As used herein, “network non-participatingsolvent” refers to organic solvents that decrease the viscosity of thenon-Newtonian ink composition, measured at any functional shear rate. Assuch, the present non-Newtonian ink compositions can be altered based onthe types of organic solvents used. For example, when the non-Newtonianink composition comprises a network participating solvent, thestructured network can be strengthened, e.g., the viscosity of thenon-Newtonian ink composition can be increased. However, when a networknon-participating solvent is used, the structured network can beweakened, e.g., the viscosity of the non-Newtonian ink composition canbe decreased. In one example, network participating solvents can includeethylhydroxy-propanediol (EHPD), glycerol, 1,5pentanediol, ethyleneglycol, triethylene glycol, and mixtures thereof In another example,network non-participating solvents can include 2-pyrrolidinone, 1,2pentanediol, MPdiol, 1,2 hexanediol, and mixtures thereof. As such, thestructured network properties, and resultant non-Newtonian inkcomposition properties can be modified by mixing and matching particularorganic solvents. In one example, the organic solvent comprises amixture of a network participating solvent and a networknon-participating solvent. Additionally, the present inks can contain asignificant amount of organic solvent, including network participatingsolvents and/or network non-participating solvents. In some examples,the organic solvent comprises only a network participating solvent, or amixture of network participating solvent and network non-participatingsolvent.

In some other examples, the organic solvent is a network participatingsolvent selected from the group consisting of ethylhydroxy-propanediol,glycerol, 1,5 pentanediol, ethylene glycol, triethylene glycol, andmixtures thereof; or the organic solvent is a network non-participatingsolvent selected from the group consisting of 2-pyrrolidinone,2-hydroxyethyl-2-pyrrolidinone, 1,2 pentanediol,2-methyl-1,3-propanediol, 1,2 hexanediol, and mixtures thereof

Photo-Initiator

The non-Newtonian photo-curable ink composition described hereinincludes a photo-initiator. The photo-initiator, or UV initiator, is anagent that initiates a reaction (i.e. polymerization) upon exposure to adesired wavelength of UV light to cure the ink composition, as describedherein, after its application to an ink-receiving material or substrate.In some examples, the photo-initiator is a radical photo-initiator. Thephoto-initiator may be a single compound or a mixture of two or morecompounds. It can be present, in the ink composition, in an amountsufficient to cure the applied ink composition. In some examples, thephoto-initiator is present in an amount representing from about 0.01 toabout 10 wt %, or from about 0.5 to about 5 wt % by weight, or fromabout 1 to about 2 wt % by weight, based on the total weight of thenon-Newtonian photo-curable ink composition.

The photo-initiator can be a water-soluble or a water-dispersiblephoto-initiator and is incorporated into the aqueous phase of the inkcomposition. In some examples, the photo-initiator is a hydrophobicphoto-initiator. The photo-initiator may be a combination of fewphoto-initiators, which absorb at different wavelengths.

Examples of radical photo-initiator include, by way of illustration andnot limitation, 1-hydroxy-cyclohexylphenylketone, benzophenone,2,4,6-trimethylbenzo-phenone, 4-methylbenzophenone,diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide,2-hydroxy-2-methyl-1-phenyl-1-propanone, benzyl-dimethyl ketal,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinoprop an-1-one, orcombinations of two or more of the above. Amine synergists may also beused, such as, for example, ethyl-4-dimethylaminobenzoate,2-ethylhexyl-4-dimethylamino benzoate.

In some examples, the photo-initiator is a bis-acyl phosphine oxide typephoto-initiator or a α-(alpha)-hydroxyketone type photo-initiator. Insome other examples, the photo-initiator is a1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one (suchas Irgacure® 2959 available from BASF). Other examples of suitablephotoinitiators include α-aminoketones, monoacylphosphine oxides,diacylphenylphosphine oxide, etc.

The photo-curable ink composition may include a UV stabilizer, i.e. anagent that can assist with scavenging free radicals. Examples of UVstabilizers include, by way of illustration and not limitation, quininemethide (Irgastab® UV 22 from BASF Corporation) and Genorad® 16 (RahnUSA Corporation) and combinations thereof

Examples of commercially available photo-initiators can be found underthe trade name Irgacure® for the BASF Corporation.

In some examples, a photosensitizer may be used with the photo-initiatorin amounts ranging from about 0.01 to about 10 wt %, or from about 1 toabout 5 wt %, based on the total weight of the ink composition. Aphotosensitizer absorbs energy and then transfers it to anothermolecule, usually the photo-initiator. Photosensitizers are often addedto shift the light absorption characteristics of a system. Suitableexamples of photosensitizers include, but are not limited tothioxanthone, 2-isopropylthioxanthone and 4-isopropylthioxanthone

Colorant

The present non-Newtonian photo-curable ink composition can include oneor more colorants that impart the desired color to the printed itemand/or to the ink. In some examples, the non-Newtonian photo-curable inkcomposition further comprises a colorant. Such colorants can be pigmentsand/or dyes. In one aspect, the colorant is a pigment, and in anotheraspect, the colorant is a dispersed pigment. In some examples, the inkcompositions include one or more pigments as colorants. The pigments canbe self-dispersed pigments, polymer-coated pigments, or common pigmentssuch as milled pigments, for example. A separate dispersing agent may beused to enable appropriate suspension of the pigment in the inkcomposition. The particulate pigment may be inorganic or organic. Thepigment can be of any color including, but not limited to, black, blue,brown, cyan, green, white, violet, magenta, red, orange and yellow, aswell as spot colors from mixtures thereof

The amount of colorant in the photo-curable ink composition depends on anumber of factors, for example, the nature of the colorant, the natureof the use of the ink composition, the nature of the jetting mechanismfor the ink, and the nature of any additives, for example. The inkcomposition may contain up to 20 wt % of colorant.

In some example, the colorant is a pigment. The amount of pigment in thephoto-curable ink composition can represent from about 0.1 to about 15wt %, or from about 1 to about 10 wt %, or from about 2 to about 8 wt %,or from about 3 to about 7 wt % based on the total weight of the inkcomposition.

The colorant can be a dye, including one or more of the many watersoluble dyes that can be used in the inkjet fields. Examples includedirect dyes, vat dyes, sulphur dyes, organic dyes, reactive dyes,disperse dyes, acid dyes, azoic dyes, or basic dyes. In yet otherexamples, the colorant can be a mixture of a pigment and a dye. In someother examples, the colorant is a water soluble dye. The amount of dye,in the photo-curable ink composition, can be present in an amountrepresenting from about 1 to about 10 wt %, or from about 2 to about 8wt %, or from about 3 to about 5 wt % based on the total weight of theink composition. Examples of such commercially available dye, couldinclude Pro-Jet Cyan 1, Pro-Jet® Yellow 1, and Pro-Jet® Magenta 1 orPro-Jet® Fast Black 1 all available from Fujifilm Imaging Colorants.

Examples of organic pigments that may be present in the photo-curableink composition include, by way of illustration and not limitation,perylene, phthalocyanine pigments (for example, phthalo green, phthaloblue), cyanine pigments (Cy3, Cy5, and Cy7), naphthalocyanine pigments,nitroso pigments, mono-azo pigments, di-azo pigments, di-azocondensation pigments, basic dye pigments, alkali blue pigments, bluelake pigments, carbon black pigments, phloxin pigments, quinacridonepigments, iso-indolinone pigments, di-oxazine pigments, carbazoledi-oxazine violet pigments, alizarine lake pigments, phthaloxy aminepigments, carmine lake pigments, tetrachloroisoindolinone pigments,perinone pigments, thio-indigo pigments, anthraquinone pigments andquinophthalone pigments, and mixtures of two or more of the above andderivatives of the above. Inorganic pigments that may be present in theink composition, include, for example, metal oxides (for example,titanium dioxide, electrically conductive titanium dioxide, iron oxides(e.g., red iron oxide, yellow iron oxide, black iron oxide andtransparent iron oxides), aluminum oxides, silicon oxides), metalsulfides, metal chlorides, and mixtures of two or more thereof

The pigment component can be a dispersible pigment, such as, forexample, pigment available under the trade names Paliotol®, Heliogen®,Chromophtal®, Irgalite®, Cinquasia® (available from BASF), Hostaperm®,Novoperm® (available from Clariant), Sunfast®, Quindo® (available fromSunChemical), Special Black (available from Degussa), Kronos® (availablefrom Kronos), Kemira® (available from Kemira Pigments).

In some examples, the non-Newtonian photo-curable ink compositioncontains pigments as colorants that show little or no settling in thefluid container or printhead during the times when the ink is not movingthrough the system or when the ink is not heated.

Other Components and Additives

In some examples, the non-Newtonian photo-curable ink composition of thepresent disclosure can include a sugar alcohol. The sugar alcohol can beany type of chain or cyclic sugar alcohol. The sugar alcohol can havethe formula: H(HCHO)_(n+1)H where n is at least 3. Such sugar alcoholscan include, for examples, without limitation erythritol (4-carbon),threitol (4-carbon), arabitol (5-carbon), xylitol (5-carbon), ribitol(5-carbon), mannitol (6-carbon), sorbitol (6-carbon), galactitol(6-carbon), fucitol (6-carbon), iditol (6-carbon), inositol (6-carbon; acyclic sugar alcohol), volemitol (7-carbon), isomalt (12-carbon),maltitol (12-carbon), lactitol (12-carbon), and mixtures thereof. Insome examples, the sugar alcohol is a 5 carbon sugar alcohol or a 6carbon sugar alcohol. In yet some other examples, the non-Newtonianphoto-curable ink composition comprises a sugar alcohol that is selectedfrom the group consisting of erythritol, threitol, arabitol, xylitol,ribitol, mannitol, sorbitol, galactitol, fucitol, iditol, inositol,volemitol, isomalt, maltitol, lactitol, and mixtures thereof. In yetsome other examples, the non-Newtonian photo-curable ink composition ofthe present disclosure includes a sorbitol.

Such sugar alcohol can be present in the non-Newtonian inkjet ink in anamount ranging from about 1% to about 25% by weight based on the totalweight of the non-Newtonian inkjet ink or can be present in an amountranging from about 5% to about 15% by weight, or from 7.5% to 15% byweight. Without being linked by any theory, it is believed that theaddition of the sugar alcohol provides improved optical density as wellas excellent curl and rub/scratch resistance to the non-Newtonianphoto-curable ink composition containing it.

Other components and additives may be present in the photo-curable inkcomposition in order to improve ink properties and performances. Theadditives include, but are not limited to, one or more of surfactants,dispersing agents, rheology modifiers, biocides, anti-foaming agents,and UV stabilizers. In some examples, the photo-curable ink compositionof the present disclosure further contains one or more additivesselected from the group consisting of surfactant, dispersing agent, UVstabilizer, de-foaming agent, rheology modifiers and biocides. The totalamount by weight of additives in the ink composition is, for example,from about 0.1 to about 10 wt %, or from about 0.2 to about 5 wt %, orfrom about 1 to about 4 wt %.

Surfactants include, for example, those commercially available under thebrand names: WET® and GLIDE® (from Evonik Tego Chemie GmbH, Essen,Germany); BYK® (from BYK Chemie GmbH, Wesel, Germany); Dynax® (fromDynax Corp. Pound Ridge N.Y.); 3M Novec® (from 3M Energy and AdvancedMaterials, St. Paul Minn.); Surfynol® (from Air Products and ChemicalsInc.) and Zonyl® FSO (from DuPont de Nemours Company, Wilmington Del.).Examples of anti-foaming agents are those commercially available underthe brand names: Foamex® and Twin® (from Evonik Tego Chemie ServiceGmbH); BYK® (from BYK Chemie GmbH); and Surfynol® (from Air Products andChemicals, Inc.). Examples of dispersants include high molecular weightcopolymers with groups having an affinity for a pigment. Specificexamples of dispersants include those commercially available from BYKChemie GmbH under the brand names BYK®. Examples of rheology modifiersinclude those commercially available under the brand names: Acrysol®(from Rohm & Haas); Borchigel® (from OMG Borchers GmbH, Langenfield,Germany); BYK (from BYK Chemie GmbH); and DSX® (from Cognis GmbH,Monheim am Rhein, Germany).

Manufacturing Method

Example of a method of manufacturing a non-Newtonian photo-curable inkcomposition comprise: adding a polymerizable FMOC material to water andto an organic solvent to form a solution or dispersion and adding aphoto-initiator in order to produce a composition comprising apolymerizable FMOC material in an amount ranging from about 2 wt % toabout 20 wt % by total weight of the ink composition; and having a firstdynamic viscosity ranging from 25 cps to 10,000 cps at a first state anda second dynamic viscosity ranging from 1 cps to 50 cps at a secondstate; subjecting the combination to conditions under which the inkcomposition becomes substantially uniform; and subjecting thecombination to filtration.

The present method can further comprise mixing a colorant into thenon-Newtonian photo-curable ink composition. In one example, thecolorant can be a pigment. As discussed herein, such pigments can beself-dispersed or can further include dispersants, e.g., a polymerdispersant. In another example, the colorant can be a dye, or a mixtureof pigment and dye.

The present disclosure refers therefore to a method for preparing theabove mentioned non-Newtonian photo-curable ink composition. The methodincludes providing, in combination, a polymerizable FMOC material, anorganic solvent, a photo-initiator and water; subjecting the combinationto conditions under which the ink composition becomes substantiallyuniform and has viscosity and surface tension suitable for being jetted;and subjecting the combination to filtration.

In some examples, conditions for rendering the ink composition to asubstantially uniform dispersion include, for example, agitation suchas, e.g., one or more of mixing, stirring, shaking, homogenizing,sonication, ultra-sonication, micro-fluidization, bead milling, andblending, for example, or a combination of the above. The phrase“substantially uniform” means that there is no visible phase separationand that the ink composition applied by draw down results in a uniformfilm without visible defects such as de-wetting, clustering, or airbubbles, for example. The ink composition may be filtered to removelarge particles that may prohibit reliable jetting. Filtration may becarried out using, by way of illustration and not limitation, one ormore of membrane filtration, surface filtration, depth filtration,screen filtration, for example.

Printing Method

The present non-Newtonian photo-curable ink composition can be used inconjunction with multiple imaging systems, non-limiting examples ofwhich include thermal inkjet system or piezo inkjet system. Thenon-Newtonian photo-curable ink compositions that are described hereinare useful in standard inkjet printing systems. The present inkcompositions can be inkjet printed as the viscosity of the non-Newtonianinkjet inks are lowered using thermal control or mechanical controlwithin a printing system, e.g., an inkjet printhead. Once exiting theprinthead, the viscosity of the present non-Newtonian inkjet inksrapidly increases (e.g. within few seconds or instantly) viaself-assembly of a polymerizable material within the non-Newtonianinkjet inks

A method of printing a non-Newtonian photo-curable ink composition cancomprise: subjecting a non-Newtonian photo-curable ink composition,having a first dynamic viscosity ranging from 25 cps to 10,000 cps, tosufficient thermal energy or mechanical energy to generate a seconddynamic viscosity ranging from 1 cps to 50 cps, wherein thenon-Newtonian photo-curable ink comprises a polymerizable FMOC materialin an amount ranging from about 2 wt % to about 20 wt % by total weightof the ink composition, an organic solvent, a photo-initiator and water;providing a media substrate; ejecting droplets of the non-Newtonianphoto-curable ink composition while at the second dynamic viscosity; andapplying photo energy to the ink composition once printed on the mediasubstrate, said photo energy having a frequency and energy levelsuitable for curing the photo-curable ink composition.

In some examples, the method of printing a non-Newtonian photo-curableink composition further comprises a drying step where the ink is driedafter printing or jetting the ink composition on the substrate and priorto the curing step.

The method of printing the non-Newtonian photo-curable ink compositioncan comprise subjecting the non-Newtonian ink composition, having afirst dynamic viscosity ranging from 25 cps to 10,000 cps at roomtemperature, to sufficient thermal energy or mechanical energy in orderto generate a second dynamic viscosity ranging from 1 cps to 50 cps. Theshear or thermal thinning can occur to jet the ink from the inkjetarchitecture in one example. In some other examples, the method furtherincludes ejecting droplets of the non-Newtonian inkjet ink while at thesecond dynamic viscosity. The steps of subjecting and ejecting can becarried out sequentially or simultaneously.

In some examples, the method of printing a non-Newtonian photo-curableink composition comprises shearing a non-Newtonian photo-curable inkcomposition, which has a first dynamic viscosity ranging from 25 cps to10,000 cps at a shear rate of 5 s⁻¹, within a printhead of an inkjetprinting apparatus at a shear rate of 10,000 s-1 or more to provide asecond dynamic viscosity ranging from 1 cps to 50 cps, wherein the inkcomposition comprises a polymerizable FMOC material in an amount rangingfrom about 2 wt % to about 20 wt % by total weight of the inkcomposition, a photo-initiator, an organic solvent and water; providinga media substrate; ejecting droplets of the non-Newtonian photo-curableink composition; and applying photo energy to the ink composition onceprinted on the media substrate, said photo energy having a frequency andenergy level suitable for curing the photo-curable ink composition.

In some other examples, the method of printing a non-Newtonianphoto-curable ink composition comprises heating a non-Newtonianphoto-curable ink composition, which has a first viscosity ranging from100 cps to 10,000 cps at a temperature of 25° C., to a temperature of atleast 50° C. to provide a second viscosity ranging from 1 cps to 10 cps,wherein the ink composition comprises a polymerizable FMOC material inan amount ranging from about 2 wt % to about 20 wt % by total weight ofthe ink composition, a photo-initiator, an organic solvent and water;providing a media substrate; ejecting droplets of the ink compositiononto said media; and applying photo energy to the ink composition onceprinted on the media substrate, said photo energy having a frequency andenergy level suitable for curing the photo-curable ink composition.

In some examples, the projection of stream of droplets of inkcomposition, onto the media substrate, is done via inkjet printingtechniques. The ink composition may be established on the material viaany suitable printing techniques, such techniques include thermal,acoustic, continuous and piezoelectric inkjet printing. In inkjetprinting devices, liquid ink drops are applied in a controlled fashionto an ink-receiving substrate, or media substrate, by ejecting inkdroplets from a plurality of nozzles, or orifices, in a printhead of aninkjet printing device or inkjet printer. In drop-on-demand systems, adroplet of ink is ejected from an orifice directly to a position on thesurface of an ink-receiving substrate, or media substrate, by pressurecreated by, for example, a piezoelectric device, an acoustic device, ora thermal process controlled in accordance with digital data signals.For inkjet printing, the ink composition can be heated or chilled to anappropriate dispensation temperature, prior to ejecting the inkcomposition to the surface of a substrate. In some examples, theprojection of stream of droplets of ink composition, onto the mediasubstrate, is done via a piezoelectric printhead.

For inkjet printing, the ink composition is heated or chilled to anappropriate dispensation temperature prior to ejecting the inkcomposition to the surface of a substrate. The particular temperatureand viscosity of the ink composition is dependent on, for example, theparticular method and equipment for conducting the inkjet printing.

The present printed or jetted ink may be dried after jetting the inkcomposition in a predetermined pattern onto the substrate in view ofevaporating the water content of the ink. The drying stage may beconducted, by way of illustration and not limitation, by hot air,electrical heater or light irradiation (e.g., IR lamps), or acombination of such drying methods. In order to achieve a targetedperformance level, it is advisable to dry the ink at a maximumtemperature allowable by the substrate that enables good image qualitywithout substrate deformation. Consequently, the substrate deformationtemperature should not be exceeded while drying. Examples of atemperature during drying is from about 40° C. to about 150° C., orabout 50° C. to about 80° C., for example. The ink composition accordingto the principles herein enables printing on plastic materials whiledrying at relatively low temperatures of about 40° C. to about 70° C.,or about 50° C. to about 60° C., for example, and while achieving fastdrying time and good image quality.

According to the printing method, once established on the mediasubstrate, the printed or jetted ink composition is cured by applyingphoto energy to the ink composition. Said photo energy having afrequency and energy level suitable for curing the non-Newtonianphoto-curable ink composition. In such curing step, a mercury or similarlamp can be used in order to fully cure and cross link the inkcomposition to the media substrate. For applying photo energy, thenon-Newtonian photo-curable ink composition, on the media substrate, maybe subjected to suitable light sources for curing the ink compositionsin accordance with the principles described herein. Ultraviolet (UV)radiations can be used to cure the ink composition as described above.Curing radiation can be UV radiation radiated by UV lamps, blue lasers,UV lasers, or ultraviolet LEDs, for example. The curing radiation may beprovided by a source of ultraviolet radiation operating in a continuousmode. The curing radiation may also be provided by a source ofultraviolet operating in a flash or pulsed mode. In some examples, theink composition is cured by using, for example, a wide arc mercury lamp,in order to fully cure and crosslink the ink.

In accordance with the principles described herein, the photo-curableink compositions find uses as ink compositions for inkjet printers. Insome examples, the photo-curable ink compositions may be dispensed tothe surface of a broad range of substrates employing inkjet technologyand equipment. A suitable inkjet printer, according to the presentmethod, is an apparatus configured to perform the printing and inkcuring processes. The printer may be a single pass inkjet printer or amulti-pass inkjet printer. The printer may include a temperaturestabilization module operative to ensure maintenance of the range of inkjetting temperatures.

As mentioned, the photo-curable ink composition is jetted onto a mediasubstrate. The media substrate may be planar, either smooth or rough, orhave any other shape that is suitable for the particular purpose forwhich it is employed. The media substrate can have a thickness in therange of about 0.1 mm to about 10 mm or in the range of about 1 mm toabout 5 mm. The media substrate may be porous or non-porous, rigid,semi-rigid, or flexible, for example. Planar media substrates may be inthe form, for example, of a film, plate, board, or sheet by way ofillustration and not limitation. Examples of media substrate include,but are not limited to, plastic substrates (for example, polyethyleneterephthalate, polyethylene, polystyrene, polypropylene, polycarbonate,and acrylic), paper, paper laminated with plastic (for example,polyethylene, polypropylene, or polystyrene), cardboard, paperboard,foam board, and textiles. The media can also be rigid PVC(polyvinylchloride rigid substrate) or PETG (Polyethylene TerephthalateGlycol-modified),In some examples, the media substrate is non-porous andhas low surface tension. Non-limiting examples include plastics, PVC,banner paper, and polypropylenes, and synthetic paper, such as Yupo®synthetic paper. Banner paper is specifically configured for printingbanners, has a smooth surface, and is often designed for color printing.The term “non-porous” includes surfaces that can have relatively poorwater permeability, absorption, and/or adsorption. Vinyl and otherplastic sheets or films, metals, coated offset media, glass, and othersimilar substrates are considered non-porous. In some embodiments, themedia substrate can be a plastic substrate. In some other embodiments,the media substrate is a rigid plastic substrate. In some examples, themedia substrate is a polypropylene, a polyvinyl chloride (PVC), anacrylic or a polycarbonate substrate. In some other examples, the mediasubstrate is a polyvinyl chloride (PVC) or a polycarbonate substrate.The media substrates can be non-swellable and/or are non-polar. Bynon-swellable, it is meant herein that the substrate surface is notswelled by any components of the ink, and no chemical bonds are formedbetween ink and substrate. By non-polar, it is meant herein that thesubstrate surface is charge-neutral, therefore adhesion to it isdifficult to achieve.

EXAMPLES

Ingredients:

TABLE 1 Ingredient name Nature of the ingredient supplier(S)-3-(FMOC-amino)- Polymerizable FMOC Sigma-Aldrich 5-hexenoic acidmaterial Irgacure ® 2959 Photo-initiator BASF Cab-O-jet ® 300 DispersedCarbon Cabot Corporation Black pigment Pro-Jet ® Cyan 1 Dye FujifilmImaging Colorants Surfynol ® 465 surfactant Air products 2-Pyrrolidinoneorganic solvent Alfa Aesar 2-Ethyl-2- organic solvent Sigma-Aldrich(hydroxymethyl)-1,3- propanediol (EHPD)

Example 1 Ink Composition

Different non-Newtonian photo-curable inkjet ink compositions areprepared with the components and the amounts as listed in Table 2. Allamounts are percentages expressed in wt % of the total weight of the inkcomposition.

TABLE 2 Components Ink # 1 Ink # 2 Ink # 3 Ink # 4(S)-3-(FMOC-amino)-5-hexenoic 3 8 15 8 acid 2-Pyrrolidinone 6 6 6 6 EHPD6 6 6 6 Irgacure ® 2959 1 1 1 1 Cab-O-jet ® 300 2.5 2.5 2.5 — Pro-Jet ®Cyan 1 — — — 3 Surfynol ® 465 0.2 0.2 0.2 0.2 Water Balance BalanceBalance Balance pH (adjusted with KOH) 9 9 9 9

Example 2 Print Performances

The ink compositions 1 to 4 are printed on different paper-based media(HP® Multipurpose Paper ColorLok® (International Paper Company; StaplesCopy Paper (Made from Staples), Georgia Pacific copy paper (GeorgiaPacific) and also on a porous media substrate (corrugated board).Printing is performed at various percentages with 1200×1200 dpi andvarious ink flux (ng/300 dpi).

The ink compositions are printed using a HP printer. The jetting step isfollowed by 1 min drying under hot air at a temperature of about 40° C.Immediately after drying, the printed image is cured by passing theprinted image under a broad range UV lamp once at a print speed of about0.5 m/s. The drying step is performed using a resistive heater withconvection. The curing step is performed using conveyor curing unit(from Uvexs Inc.).

The resulting printed articles are evaluated for their adhesionperformance and print quality (OD). Adhesion testing is performedaccording to ASTM 3359 “Measuring Adhesion by Tape Test”. Cuts are madeto the printed sample by a cross hatch cutter such as Elcometer®1542Cross Hatch Adhesion Tester (Elcometer Inc., Rochester Hills, Mich.).Adhesive tape (3M Scotch® tape 250), is placed and smoothed over the cutarea. The tape is then removed rapidly in one movement and the cut areais inspected. The results are reported according to the removal of inkfrom the substrate. The print quality (or ink efficiency) is evaluatedby measuring the Optical density of the image (as OD provided by mass ofink). The optical densities are measured using Gretag Macbeth®Spectrolino densitometer.

The ink compositions according to the present disclosure have excellentprint quality (ink efficiency) and show improved adhesion performances;such results being independent of the type of media used: treated(ColorLok®) and untreated paper (Staples Copy Paper).

1. A non-Newtonian photo-curable ink composition, comprising: a. apolymerizable FMOC material in an amount ranging from about 2 wt % toabout 20 wt % by total weight of the ink composition, b. aphoto-initiator, c. an organic solvent, d. and water, wherein the inkcomposition has a first dynamic viscosity ranging from 25 cps to 10,000cps at a first state and a second dynamic viscosity ranging from 1 cpsto 50 cps at a second state.
 2. The non-Newtonian photo-curable inkcomposition of claim 1, wherein the ink composition has a dynamicviscosity ranging from 25 cps to 10,000 cps at a temperature of 25° C.and a dynamic viscosity ranging from 1 cps to 50 cps at a temperature of50° C.
 3. The non-Newtonian photo-curable ink composition of claim 1,wherein the ink composition has a dynamic viscosity ranging from 25 cpsto 10,000 cps at a shear rate of 5 s⁻¹ and a dynamic viscosity rangingfrom 1 cps to 50 cps at a shear rate of 10,000 s⁻¹ measured at 25° C. 4.The non-Newtonian photo-curable ink composition of claim 1 wherein thepolymerizable FMOC material has the formula

wherein R1 is a polymerizable or curable amino acid or peptide.
 5. Thenon-Newtonian photo-curable ink composition of claim 1 wherein thepolymerizable FMOC material is a polymerizableN-(9-fluorenylmethoxycarbonyl)-L-phenylalanine.
 6. The non-Newtonianphoto-curable ink composition of claim 1 wherein the polymerizable FMOCMaterial comprises N-methacryloyl 3,4-dihydroxy-L-phenylalanine methylester or α-Vinyl-DL-phenylalanine as polymerizable group.
 7. Thenon-Newtonian photo-curable ink composition of claim 1 wherein theorganic solvent is a network participating solvent selected from thegroup consisting of ethylhydroxy-propanediol, glycerol, 1,5 pentanediol,ethylene glycol, triethylene glycol, and mixtures thereof or the organicsolvent is a network non-participating solvent selected from the groupconsisting of 2-pyrrolidinone, 1,2 pentanediol,2-methyl-1,3-propanediol, 1,2 hexanediol, and mixtures thereof.
 8. Thenon-Newtonian photo-curable ink composition of claim 1 wherein theorganic solvent is present in an amount ranging from about 3 wt % toabout 50 wt % by total weight of the ink composition.
 9. Thenon-Newtonian photo-curable ink composition of claim 1 wherein theorganic solvent comprises only a network participating solvent, or amixture of network participating solvent and network non-participatingsolvent.
 10. The non-Newtonian photo-curable ink composition of claim 1wherein the photo-initiator is present in an amount representing fromabout 0.01 wt % to about 10 wt % based on the total weight of inkcomposition.
 11. The non-Newtonian photo-curable ink composition ofclaim 1 wherein the photo-initiator is a bis-acyl phosphine oxide typephoto-initiator or a α-(alpha)-hydroxyketone type photo-initiator. 12.The non-Newtonian photo-curable ink composition of claim 1 that furthercomprises a colorant.
 13. The non-Newtonian photo-curable inkcomposition of claim 1 that further comprises a sugar alcohol isselected from the group consisting of erythritol, threitol, arabitol,xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol,inositol, volemitol, isomalt, maltitol, lactitol, and mixtures thereof.14. An aqueous ink composition having non-Newtonian propertiescomprising a photo-initiator and a structured network that is formed byFMOC material that comprises a polymerizable or curable amino acid orpeptide
 15. A method for manufacturing a non-Newtonian photo-curable inkcomposition comprising: a. adding a polymerizable FMOC material to waterand to an organic solvent to form a solution or dispersion and adding aphoto-initiator in order to produce a composition comprising apolymerizable FMOC material in an amount ranging from about 2 wt % toabout 20 wt % by total weight of the ink composition; and having a firstdynamic viscosity ranging from 25 cps to 10,000 cps at a first state anda second dynamic viscosity ranging from 1 cps to 50 cps at a secondstate; b. subjecting the combination to conditions under which the inkcomposition becomes substantially uniform; c. and subjecting thecombination to filtration.